A general theory of acts leads to a theory of cognition distinguishing between formation of apriorical knowledge about values, norms, and cognitive beliefs, based on conditioning by means of rewards and punishments, and formation of aposteriorical knowledge based on conscious, theoretical analysis of observations. The latter, rational layer of consciousness can be built on the former, irrational layer only, if certain conditions are fulfilled. It is shown that rational cognition of values presupposes a notion of aposteriorical value, which challenges some conventions of the 'value-free' social science, in particular, the so called guillotine of Hume